Neuro 24 them had their brain's gray matter change + or - in different parts, the longer in space the more the change. Now then, according to Google Search of human brain; "Overall, gray matter occupies 40 percent of the cerebrum," and it turns out when you look at a Dolphin brain although structurally different it contains a lot of gray matter (Cite: 2, 3, 4). And, and really it is said that it's our 'gray matter' that makes us human, separates us from Dolphins (cite: 5). The human brain has much more by percentage, even though it is smaller in size than a dolphin brain - maybe dolphin brains don't need as    https://pilpedia.com/neuro-24/